Abstract: The aim of this study is to obtain a more accurate soil-water characteristic curve (SWCC). First of all, major influential factors in the process of measuring matric suction by pressure plate are analyzed. Air dissolution in water is identified to have influence on the test result, which should be taken into consideration in measuring the SWCC. According to the solubility of air in water, the volume of dissolved air in water in the drainage channel is determined, and the measured value of bubble volume at the bottom of clay plate is corrected. On the basis of this corrected bubble volume, a correction formula for the volumetric water content in soil sample is proposed to acquire a more reasonable SWCC.

Key words: SWCC, pressure plate, matric suction, solubility, drainage channel